Conversion rate is one of the most important metrics in digital marketing, yet it is also one of the most inconsistently defined. Founders often encounter the term without a clear understanding of what it is measuring, how to improve it, or what a good rate looks like for their type of business. Understanding the concept clearly is foundational to evaluating the effectiveness of any marketing channel.
A conversion rate is the percentage of people who take a desired action after encountering a piece of marketing or a web page. The action being measured depends on the context: making a purchase, submitting an enquiry, signing up for an email list, or booking a call. Conversion rate is calculated by dividing the number of conversions by the number of visitors or interactions, expressed as a percentage. It is one of the most direct measures of how effectively marketing spend translates into commercial outcomes.
Improving conversion rate — known as conversion rate optimisation or CRO — involves testing and refining the elements that influence whether visitors take the desired action: the clarity of the offer, the strength of the call to action, the trust signals present, and the ease of the process. Our guide to conversion rates for UK founders covers how to measure, interpret, and improve this metric across different channels.